1. Field of the Invention
The present invention relates to an image sensor package and its manufacturing method.
2. Description of the Related Art
In general, image sensors are devices which sense the information regarding objects to be photographed and transform it into video signals. Such devices may be classified into camera tubes, such as vidicons and plumbicons, and solid image sensors, such as complementary metal oxide semiconductors (CMOSs) and charge coupled devices (CCDs). When an image sensor is manufactured as the solid image sensor, it is generally used as a type of sensor wherein a lens is coupled to a semiconductor package which contains a semiconductor die for image sensors therein.
Conventional image sensor packages are composed of a glass substrate having electrically conductive patterns formed thereon and an image sensor die coupled to the electrically conductive patterns of the glass substrate via electrically conductive bumps. Such image sensor packages have an underfill formed between the glass substrate and the image sensor die, in order to improve the coupling force between the glass substrate and the image sensor die and to protect the sensing portion which is formed on the image sensor die. Such an underfill is generally of a type which surrounds the electrically conductive bumps.
However, such conventional image sensor packages, which use an underfill having low viscosity, have a problem in that the underfill may flow to the sensing portion of the image sensor die and degrade the performance of the image sensor die. This, of course, decreases the overall production yield of the package.
In addition, since the underfill cannot completely interrupt moisture, a large amount of moisture may be distributed, under certain conditions, between the glass substrate and the sensing portion formed on the image sensor die. Such a large amount of moisture formed on the sensing portion, of course, degrades the sensing function of the image sensor package in a drastic manner.
For above underfill process, at least a predetermined distance must be secured between solder balls, which are connected to the glass substrate, and the electrically conductive bumps. This increases the overall size of the package. Such an increase of size of the package acts as a hindrance to the current trend of making electronic products in a compact size.
Furthermore, additional equipment is necessary for the underfill process. This increases the manufacturing cost and makes the manufacturing process more complicated. In particular, expensive underfill dispensing equipment increases the manufacturing cost of the package, and the additional underfill process, which must be performed after the glass substrate and the image sensor die are coupled to each other, makes the process more complicated.